Loop adds a closed loop at a point using the last line type you picked; to put a loop inside a line, select the line and press Add loop. Select to move vertices, labels and lines, or to edit them. Delete removes the selection, Ctrl/⌘ Z undoes. In labels, ^ and _ make super- and subscripts (e^+, W^{\pm}, ν_e) and \bar{q} puts a bar over a letter.

The grouped particle-label palette was inspired by the Feynman diagram maker at aidansean.com.